Heretofore, numerous types of soft drink dispensers have been known. In such dispensers, a flavored syrup is mixed with another liquid such as water, carbonated water or soda to achieve the composite drink. Prior soft drink dispensers of this nature have been typically slow in operation due to the foaming action which resulted when the syrup and soda are mixed, particularly at fast flow rates. The prior art teaches that the syrup and soda be mixed in a dispensing head by means of a mechanical diffuser. The joining of the syrup with the soda within the dispensing head causes foam to be generated in the head itself such that foam, rather than liquid, is dispensed. As a result, dispensing the drink must be done in steps with intermittent pauses introduced by the operator to allow the foam to settle. Such pauses delay the dispensing operation and, in a fast service environment, become extremely costly. The problem of foaming has further been found to arise from the fact that the syrup and soda are continuously poured together rather than staged or phased with respect to each other. Finally, foaming has been found to be a problem in virtually all dispensed carbonated beverages, not only slowing the dispensing cycle, but resulting in a "flat" drink due to the attendant reduction in carbonation level.
The prior art soft drink dispensers have also demonstrated an inconsistency in drink formulation as a function of temperature. It is known that sugar-based soft drink syrups are temperature sensitive and, for a given pressure head, the rate of syrup flow varies as a function of the temperature of the syrup. More particularly, the relationship between syrup flow rate and temperature is of a general exponential nature. The rate of syrup flow also varies from syrup to syrup as a function of the syrup composition. The prior art has taught a relational flow of syrup and soda to achieve the desired consistency, but has provided no means for compensating for such relation as a function of syrup temperature or composition. Indeed, the prior art has taught the use of mechanically regulated flow controls including metering screws for achieving the desired adjustment of syrup dispensing rates, but such controls must be manually adjusted and are generally ineffective in compensating for temperature and pressure variations in the relationship between the components of the beverage. Further, such mechanical controls have typically been a source of operational problems in that they are prone to clog due to the increased viscosity at lower temperatures and to the crystalline nature of the syrup.
The prior art has suggested monitoring syrup temperature at the dispensing head, but not at various points in the dispensing system. However, it is known that the syrup temperature may vary from point to point throughout the system. If syrup temperature in any portion of the apparatus changes but a few degrees, the resultant viscosity change will tend to vary the syrup flow at the dispensing station. Accordingly, monitoring syrup temperature at various points within the system is necessary to institute appropriate compensation to achieve the desired flow rates for beverage consistency.
It has further been known that prior art soft drink dispensers have generally been inflexible with respect to dispensing low carbonation drinks or those having a soda component different from the usual 5 parts of water or carbonated water to 1 part of syrup. While it has been known to add a pure water source to the dispensing cycle of low carbonation drinks to lower the effective carbonation level, the degree of carbonation variability has been extremely limited. No known system has provided for a virtually infinite degree of variability of the carbonation level by varying the flow of water and/or carbonated water to the soft drink.
The prior art has failed to recognize the benfits of rechambering the syrup for soft drinks in a separate pump or chamber from which it may be dispensed for combination with other components for the formulation of the soft drink. Instead, prior systems have typically dispensed the syrup from the bulk tank or canister in which it is received to the dispensing station. Such prior dispensing systems have accordingly been Plagued with problems of line pressure variation, viscosity changes, considerations to be given line length and diameter, and the like. In like manner, these prior systems have required high pressures of CO.sub.2 gas at the source or canister to pump the syrup to the dispensing head, such pressures often resulting in carbonation of the syrup itself. The resultant volatile nature of the syrup made it difficult to dispense.
In the prior systems, when the canister emptied of syrup the dispensing line from the canister to the dispensing head would fill with gas pockets or slugs such that the entire length of the line would be a combination of gas and syrup. After the empty canister was replaced, the drinks dispensed until the line became completely filled with syrup would be quite weak and the dispensing would be sporadic due to gas slugs in the line. The prior art remedied this problem by purging the line through the dispensing head after replacement of the canister, but only at the expense of wasted time, syrup, and CO.sub.2 gas.
The prior art failed to recognize the benefits which could be obtained by consolidating the syrup from various canisters for dispensing from a single pump, eliminating the aforesaid problems and allowing the system to operate from any backroom container or pumping source, whether it be pressure, mechanical, gravity, or other nature. It similarly failed to recognize the benefits of venting a rechambered pump to prevent carbonation of the syrup.
Previous attempts to remedy certain of the foregoing problems have included the so-called "bag-in-the-box" approach, but with limited success. Such systems remain incapable of properly compensating for line temperature/pressure changes which occur between the pump and dispensing head. Additionally, high CO.sub.2 pressures were found necessary to drive the pumps for such systems with the inherent short coming of excessive cost to maintain such pressures.
Known soft drink systems generally require on-site adjustment of brix level, tailored to the line lengths, backroom pressure settings, ambient temperature and the like at the system location. These prior systems simply are not conducive to factory adjustment of brix because the dispensing characteristics of such systems are site dependent.
Typical soft drink dispensers have a separate dispensing head or faucet to dispense each brand or type of soft drink, complicating the structure and operation of the system. Those systems which have sought to use a single dispensing head for all types of soft drinks have generally experienced a cross mix of brands resulting from residue remaining in the head after a dispensing cycle.
It has further been known that exposure of soft drink syrup to the air tends to contaminate or rapidly age the syrup, significantly reducing beverage quality. Further, failure of the prior art to monitor the system for the detection of malfunctions and timely termination of the operation thereof has often resulted in a reduction in drink quality and concomitant rise in cost of operation.
The prior art has further been devoid of means for efficiently cooling the soda at start-up, requiring either a significant delay between energization of the system and the dispensing of beverages or a degradation in the quality of beverages initially dispensed. Yet further, the prior art has been devoid of a soft drink dispenser capable of floating syrup at the end of a dispensing cycle without resulting in a residue of such syrup being dispensed into the next soft drink or without changing the brix or sweetness level of the beverage.